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Orion Bullets

This composite image at infrared wavelengths was obtained using the Gemini North laser guide star system in conjunction with the ALTAIR adaptive optics system and the NIRI near-infrared imager. The image shows the Orion "bullets" as blue features and represents the light emitted by hot iron (Fe) gas. The light from the wakes, shown in orange, is from excited hydrogen gas.

The Orion Nebula is a star-forming region located relatively near to us, about 1,500 light-years away. It's a young stellar nursery and shows many unusual features related to the effect of massive stars on the dense birth environment of gas and dust.

The Orion bullets were first seen in a visible-light image in 1983. By 1992, images taken at infrared wavelengths led astronomers to conclude that these clumps of gas were ejected from deep within the nebula following an unknown violent event connected with the recent formation of a cluster of massive stars there. The bullets are speeding outward from the cloud at up to 400 kilometers (250 miles) per second. This is more than a thousand times faster than the speed of sound. The name "bullet" is somewhat misleading since these objects are truly gigantic. The typical size of one of the bullet tips is about ten times the size of Pluto's orbit around the Sun. The wakes shown in the image are about a fifth of a light-year long.

The field of view of this image is about 50 arcseconds across and structure on 0.1 arcsecond (2 pixel) scales is visible.

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